Curable Photochromic Compositions

ABSTRACT

A curable photochromic composition can include: (a) a first component having a first compound with at least two active hydrogen-functional groups and an active hydrogen-functional group equivalent weight of at least 1000; (b) a second component having at least one of a polyisocyanate and a blocked polyisocyanate; and (c) at least one photochromic compound. The ratio of total isocyanate and blocked isocyanate equivalents of the second component to total active hydrogen-functional group equivalents of the first component is at least 4:1.

FIELD OF THE INVENTION

The present invention relates generally to curable photochromiccompositions and photochromic articles having at least one coating layerformed from the curable photochromic compositions.

BACKGROUND OF THE INVENTION

Photochromic compounds undergo a transformation from one form or stateto another form in response to radiation. Typically, upon exposure toactinic radiation, many photochromic compounds are transformed from aclosed-form, which corresponds to an unactivated state of thephotochromic compounds, to an open-form, which corresponds to anactivated (or colored) state of the photochromic compounds. In theabsence of exposure to actinic radiation, such photochromic materialsare reversibly transformed from the activated (or colored) state, backto the unactivated (or bleached) state. As such, photochromic compoundscan be incorporated into a coating and applied to a substrate to providea reversible change in color when exposed to radiation such asultraviolet light.

Because of their ability to change color when exposed to radiation,photochromic coatings are often applied over optical articles to reducethe transmission of incident light into the eye. For instance,photochromic coatings are commonly applied over sunglasses, visioncorrecting ophthalmic lenses, fashion lenses, e.g., non-prescription andprescription lenses, sport masks, face shields, goggles, visors, cameralenses, windows, and automotive windshields.

Photochromic coatings generally have a homogeneous polymeric matrix,with photochromic compounds evenly distributed within the matrix. Asphotochromic compounds undergo a change in conformation upon exposure toradiation, the hardness of the matrix affects the speed at which thecompounds can exhibit photochromic activity. Thus, by reducing thehardness of the matrix, it is possible to increase the speed at whichthe photochromic compounds are activated and unactivated. However, itwould be desirable to improve photochromic performance withoutcompromising the hardness of the coating itself.

SUMMARY OF THE INVENTION

The present invention is directed to a curable photochromic composition.The curable photochromic composition includes: (a) a first componentcomprising a first compound having at least two activehydrogen-functional groups and an active hydrogen-functional groupequivalent weight of at least 1000; (b) a second component comprising atleast one of a polyisocyanate and a blocked polyisocyanate; and (c) atleast one photochromic compound, wherein the composition has a ratio oftotal isocyanate and blocked isocyanate equivalents to total activehydrogen-functional group equivalents of at least 4:1.

The present invention is also directed to a photochromic article thatincludes (a) a substrate and (b) at least one coating layer formed froma curable photochromic composition residing over at least a portion ofthe substrate.

DESCRIPTION OF THE INVENTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers expressing, for example, quantities ofingredients used in the specification and claims are to be understood asbeing modified in all instances by the term “about”. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard variation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

In this application, the use of the singular includes the plural andplural encompasses singular, unless specifically stated otherwise. Inaddition, in this application, the use of “or” means “and/or” unlessspecifically stated otherwise, even though “and/or” may be explicitlyused in certain instances. Further, in this application, the use of “a”or “an” means “at least one” unless specifically stated otherwise.

All documents, such as, but not limited to, issued patents and patentapplications, referred to herein, and unless otherwise indicated, are tobe considered to be “incorporated by reference” in their entirety.

As used herein, molecular weight values of polymers, such as weightaverage molecular weights (Mw) and number average molecular weights(Mn), are determined by gel permeation chromatography using appropriatestandards, such as polystyrene standards, and glass transitionstemperatures (Tg) are determined using differential scanning calorimetry(DSC) or dynamic mechanical analysis (DMA).

As used herein, polydispersity index (PDI) values represent a ratio ofthe weight average molecular weight (Mw) to the number average molecularweight (Mn) of the polymer (i.e., Mw/Mn).

As used herein, the term “active hydrogen-functional group” refers to afunctional group containing a hydrogen atom that displays a significantdegree of reactivity, such as towards an isocyanate group (NCO).Non-limiting examples of active hydrogen-functional groups includehydroxyls, primary amines, secondary amines, thiols (also referred to asmercaptans), and combinations thereof.

The term “active hydrogen-functional group equivalent weight” refers tothe average molecular weight per active hydrogen-functional group andcan be determined in accordance with art-recognized methods, such as by¹H NMR or analytical titration.

A “polyol” refers to an organic molecule having an average of greaterthan 1.0 hydroxyl groups per molecule. Thus, a polycarbonate polyol, apolyether polyol, a polyester polyol, a polyamide polyol, and the likerefer to a polycarbonate, a polyether, a polyester, and a polyamidepolymer having an average of greater than 1.0 hydroxyl group, such as atleast two hydroxyl groups.

As used herein, the term “polymer” means homopolymers (e.g., preparedfrom a single monomer species), copolymers (e.g., prepared from at leasttwo monomer species), and graft polymers.

As used herein, a “polyisocyanate” refers to a molecule comprising morethan one isocyanate (NCO) functional group. A “blocked polyisocyanate”refers to a polyisocyanate in which the isocyanate groups are protectedby a blocking agent such as β-diketone, phenol, 3,5-dimethylpyrazole,cresol, epsilon-caprolactam, and methyl ethyl ketoxime, for example,which can de-block under certain conditions, such as elevatedtemperatures.

As used herein, the term “(meth)acrylate” and similar terms, such as“(meth)acrylic acid ester” means methacrylates and/or acrylates. As usedherein, the term “(meth)acrylic acid” means methacrylic acid and/oracrylic acid.

As used herein, a “soft segment domain” refers to a domain having aglass transition temperature (Tg) of equal to or less than −10° C.Further, a “hard segment domain” refers to a domain having a Tg of atleast 0° C.

As used herein, recitations of “linear or branched” groups, such aslinear or branched alkyl, are herein understood to include: a methylenegroup or a methyl group; groups that are linear, such as linear C₂-C₃₆alkyl groups; and groups that are appropriately branched, such asbranched C₃-C₃₆ alkyl groups.

As used herein, recitations of “optionally substituted” group, means agroup, including but not limited to, alkyl group, cycloalkyl group,heterocycloalkyl group, aryl group, and/or heteroaryl group, in which atleast one hydrogen thereof has been optionally replaced or substitutedwith a group that is other than hydrogen, such as, but not limited to,halo groups (e.g., F, Cl, I, and Br), hydroxyl groups, ether groups,thiol groups, thio ether groups, carboxylic acid groups, carboxylic acidester groups, phosphoric acid groups, phosphoric acid ester groups,sulfonic acid groups, sulfonic acid ester groups, nitro groups, cyanogroups, hydrocarbyl groups (including, but not limited to: alkyl;alkenyl; alkynyl; cycloalkyl, including poly-fused-ring cycloalkyl andpolycyclocalkyl; heterocycloalkyl; aryl, including hydroxyl substitutedaryl, such as phenol, and including poly-fused-ring aryl; heteroaryl,including poly-fused-ring heteroaryl; and aralkyl groups), and aminegroups, such as N(R₁₁′)(R₁₂′) where R₁₁′ and R₁₂′ can each beindependently selected from hydrogen, linear or branched C₁-C₂₀ alkyl,C₃-C₁₂ cycloakyl, C₃-C₁₂ heterocycloalkyl, aryl, and heteroaryl.

The term “alkyl” as used herein, means linear or branched alkyl, suchas, but not limited to, linear or branched C₁-C₂₅ alkyl, or linear orbranched C₁-C₁₀ alkyl, or linear or branched C₂-C₁₀ alkyl. Examples ofalkyl groups from which the various alkyl groups of the presentinvention can be selected from, include, but are not limited to, thoserecited previously herein. Alkyl groups of the various compounds of thepresent invention can include one or more unsaturated linkages selectedfrom —CH═CH— groups and/or one or more —C≡C— groups, provided the alkylgroup is free of two or more conjugated unsaturated linkages. The alkylgroups can be free of unsaturated linkages, such as CH═CH groups and—C≡C— groups.

The term “cycloalkyl” as used herein means groups that are appropriatelycyclic, such as, but not limited to, C₃-C₁₂ cycloalkyl (including, butnot limited to, cyclic C₅-C₇ alkyl) groups. Examples of cycloalkylgroups include, but are not limited to, those recited previously herein.The term “cycloalkyl” as used herein also includes: bridged ringpolycycloalkyl groups (or bridged ring polycyclic alkyl groups), suchas, but not limited to, bicyclo[2.2.1]heptyl (or norbornyl) andbicyclo[2.2.2]octyl; and fused ring polycycloalkyl groups (or fused ringpolycyclic alkyl groups), such as, but not limited to,octahydro-1H-indenyl and decahydronaphthalenyl.

The term “heterocycloalkyl” as used herein means groups that areappropriately cyclic (having at least one heteroatom in the cyclicring), such as, but not limited to, C₃-C₁₂ heterocycloalkyl groups orC₅-C₇ heterocycloalkyl groups, and which have at least one heteroatom inthe cyclic ring, such as, but not limited to, O, S, N, P, andcombinations thereof. Examples of heterocycloalkyl groups include, butare not limited to, imidazolyl, tetrahydrofuranyl, tetrahydropyranyl,and piperidinyl. The term “heterocycloalkyl” as used herein can alsoinclude: bridged ring polycyclic heterocycloalkyl groups, such as, butnot limited to, 7-oxabicyclo[2.2.1]heptanyl; and fused ring polycyclicheterocycloalkyl groups, such as, but not limited to,octahydrocyclopenta[b]pyranyl and octahydro 1H isochromenyl.

As used herein, the term “aryl” includes C₅-C₁₈ aryl, such as C₅-C₁₀aryl (and includes polycyclic aryl groups, including polycyclic fusedring aryl groups). Representative aryl groups include, but are notlimited to, phenyl, naphthyl, anthracenyl, and triptycenyl.

The term “heteroaryl,” as used herein means aryl groups having at leastone heteroatom in the ring, and includes, but is not limited to, C₅-C₁₈heteroaryl, such as, but not limited to, C₅-C₁₀ heteroaryl (includingfused ring polycyclic heteroaryl groups) and means an aryl group havingat least one heteroatom in the aromatic ring, or in at least onearomatic ring in the case of a fused ring polycyclic heteroaryl group.Examples of heteroaryl groups include, but are not limited to, furanyl,pyranyl, pyridinyl, isoquinoline, and pyrimidinyl.

As used herein, the term “fused ring polycyclic-aryl-alkyl group” andsimilar terms such as, fused ring polycyclic-alkyl-aryl group, fusedring polycyclo-aryl-alkyl group, and fused ring polycyclo-alkyl-arylgroup means a fused ring polycyclic group that includes at least onearyl ring and at least one cycloalkyl ring that are fused together toform a fused ring structure. For purposes of non-limiting illustration,examples of fused ring polycyclic-aryl-alkyl groups include, but are notlimited to, indenyl, 9H-flourenyl, cyclopentanaphthenyl, and indacenyl.

The term “aralkyl” as used herein includes, but is not limited to,C₆-C₂₄ aralkyl, such as, but not limited to, C₆-C₁₀ aralkyl, and meansan aryl group substituted with an alkyl group. Examples of aralkylgroups include, but are not limited to, those recited previously herein.

Further, the term “alkylene” refers to a linear or branched divalenthydrocarbon radical. The alkylene group may include, but is not limitedto, a linear or branched C₁-C₃₀ divalent hydrocarbon radical, or linearor branched C₁-C₂₀ divalent hydrocarbon radical, or linear or branchedC₁-C₁₀ divalent hydrocarbon radical. Alkylene groups of the variouscompounds of the present invention can include one or more unsaturatedlinkages selected from —CH═CH— groups and/or one or more —C≡C— groups,provided the alkylene group is free of two or more conjugatedunsaturated linkages. Alternatively, the alkylene groups are free of anyunsaturated linkages, such as CH═CH groups and —C≡C— groups.

The term “photochromic” refers to the capability to change color uponexposure to radiant energy such as upon exposure to visible light, forexample. Thus, a “photochromic composition” refers to a composition thatis capable of changing color upon exposure to radiant energy such asupon exposure to visible light, for example.

The term “curable”, “cure”, “cured” or similar terms, as used inconnection with a cured or curable composition, is intended to mean thatat least a portion of the polymerizable and/or crosslinkable componentsthat form the curable composition are at least partially polymerizedand/or cross-linked. The degree of crosslinking can range from 5% to100% of complete crosslinking The degree of crosslinking can range from30% to 95%, such as 35% to 95%, or 50 to 95%, or 50% to 85% of fullcrosslinking The degree of crosslinking can range between anycombination of the previously stated values, inclusive of the recitedvalues, and can be determined in accordance with art-recognized methods,such as, but not limited to, solvent-extraction methods.

The term “substrate” means an article having at least one surface thatis capable of accommodating a curable photochromic composition; namely,the substrate has a surface to which a curable photochromic compositioncan be applied. The shape the surface of the substrate can includeround, flat, cylindrical, spherical, planar, substantially planar,plano-concave and/or plano-convex, curved, including, but not limitedto, convex, and/or concave.

The terms “optical,” “optically clear,” or like terms mean that thespecified material, e.g., substrate, film, coating, etc., exhibits alight transmission value (transmits incident light) of at least 4%, andexhibits a haze value of less than 1%, e.g., a haze value of less than0.5%, when measured at 550 nanometers by, for example, a Haze Gard PlusInstrument.

The phrase “at least partially coated” means an amount of coatingcovering from a portion to the complete surface of a substrate.

As previously noted, the present invention is directed to a curablephotochromic composition. The curable photochromic composition caninclude a first component having a first compound with at least twoactive hydrogen-functional groups. The active hydrogen-functional groupsthat can be used with the first compound include, but are not limitedto, hydroxyls, primary amines, secondary amines, thiols (also referredto as mercaptan), and combinations thereof. The activehydrogen-functional groups that can be used with the compositions of thepresent invention can have an active-hydrogen equivalent weight of atleast 1,000, at least 1,500, at least 2,000, at least 2,500, or at least5,000.

Non-limiting examples of compounds comprising at least two hydroxylgroups and which can be used as the first compound include various typesof polyols comprising at least two hydroxyl groups. The polyols caninclude, but are not limited to, polycarbonate polyols, polyetherpolyols, polyester polyols, and combinations thereof.

Suitable polycarbonate polyols can be obtained, for example, byisolating higher molecular weight polycarbonate functional polyols frommixtures of polycarbonate functional polyols having a highpolydispersity index. For example, the polycarbonate functional polyolscan be obtained by isolating higher molecular weight polycarbonatefunctional polyols from a mixture of aliphatic polycarbonate polyolscommercially available as PC-1122 from Stahl USA, ETERACOLL™ PH-200D,PH-200, and UH-200 all from Ube Chemical. Other suitable polycarbonatepolyols are commercially available from Asahi under the trade nameDURANOL™ T5652.

The polycarbonate functional polyol can be purified by washing themixture with methanol or other suitable solvent and removing the lowmolecular weight fractions until the polydispersity index of theremaining sample is less than or equal to 1.50.

Further, ester linkages may be added along the backbone of thepolycarbonate polyol. Extension of the polycarbonate with polyesterfunctionality may be done using a Lewis acid catalyst (such as, but notlimited to, tin(II) ethylhexanoate, triethyl aluminum, diphenylphosphate, tri-isopropoxide aluminum, Borchi Kat® 22, dibutyltin(IV)dilaurate, etc.) or amine catalyst (such as, but not limited to,1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]-pyrimidine) by means of ringopening polymerizations (ROP). Extending the molecular weight of thepolycarbonate includes the use of ester by reacting the polycarbonatesimultaneously with lactone using ROP in the presence of a Lewis acidcatalyst such as those described previously.

Non-limiting examples of suitable polyether polyols includepolyoxyalkylene polyols and polyalkoxylated polyols, such as, forexample, the poly(oxytetramethylene)diols. The polyoxyalkylene polyolscan be prepared according to methods known in the art, such as bycondensing alkylene oxide, or a mixture of alkylene oxides using acid orbase catalyzed addition, with a polyhydric initiator or a mixture ofpolyhydric initiators such as ethylene glycol, propylene glycol,glycerol, sorbitol, and the like. Illustrative alkylene oxides includeethylene oxide, propylene oxide, butylene oxide, amylene oxide,aralkylene oxides, e.g., styrene oxide and the halogenated alkyleneoxides such as trichlorobutylene oxide. Examples of polyoxyalkylenepolyols include polyoxyethylene (i.e., polyethylene glycol) with amolecular weight of greater than 2000, polyoxypropylene (i.e.,polypropylene glycol) with a molecular weight of greater than 2000,polytetramethylene ether glycol, and combinations thereof. Esterlinkages may also be added along the backbone of the polyether polyolusing the conditions previously described. Non-limiting examples ofcommercially available polyether polyols include those available fromDow Chemicals under the VORANOL™ trade name, from BASF under theLUPRANOL®, PLURACOL®, PLURONIC®, and PolyTHF® trade names, and fromBayer under the DESMOPHEN® and ACCLAIM® trade names.

Non-limiting examples of suitable polyester polyols can include thoseprepared with polyols including, but not limited to, the previouslydescribed polyols with polycarboxylic acids. Non-limiting examples ofsuitable polycarboxylic acids include phthalic acid, isophthalic acid,terephthalic acid, trimellitic acid, tetrahydrophthalic acid, adipicacid, succinic acid, glutaric acid, fumaric acid, and combinationsthereof. Anhydrides of the above acids, where they exist, can also beemployed and are encompassed by the term “polycarboxylic acid.” Inaddition, certain materials which react in a manner similar to acids toform polyester polyols can also be used. Non-limiting examples of suchmaterials include lactones, such as caprolactone, propiolactone, andbutyrolactone, and hydroxy acids, such as hydroxycaproic acid anddimethylol propionic acid. Moreover, as used herein, the polyesterpolyols can also include polyester polyols modified with fatty acids orglyceride oils of fatty acids. The polyester polyol can also be preparedby reacting an alkylene oxide, such ethylene oxide, propylene oxide, andthe like, and the glycidyl esters of versatic acid with methacrylic acidto form the corresponding ester. Suitable polyester polyols can alsoinclude polyester diols such as polycaprolactone diol. Non-limitingexamples of commercially available polyester polyols include thoseavailable from BASF under the LUPRAPHEN® trade name, or from Evonikindustries under the DYNACOLL® trade name, or from Bayer under theDESMOPHEN® and BAYCOLL® trade names.

As previously described, the active hydrogen-functional groups of thefirst compound can also include primary and/or secondary amine groups.As such, the first compound can include polyamine compounds. Forexample, the first compound can include, but is not limited to,polycarbonate amines, polyester amines, polyether amines, andcombinations thereof.

Suitable polycarbonate amines and polyester amines that can be used asthe first compound can be synthesized using various methods known in theart. For instance, suitable polycarbonate diamines can be prepared byusing a nitrophenyl functionalized initiator for the ring opening oftrimethylene carbonate followed by reduction to the amine as describedin Macromolecules, 1997, 30, 6074, which is incorporated by referenceherein. Further, suitable polyester diamines can be prepared by thecondensation of hydroxyl terminated polyesters with N-benzyloxycarbonylamino acid followed by catalytic hydrogenation to produce the amine asdescribed in Bioconjugate Chemistry, 2002, 13(5), 1159-1162, which isincorporated by reference herein.

Non-limiting examples of polyether amines include those commerciallyavailable from Huntsman under the trade names JEFFAMINE® D-2000,JEFFAMINE® D-4000, JEFFAMINE® ED-2003, JEFFAMINE® T-5000, and JEFFAMINE®SD-2001.

In addition to the first component, the photochromic composition canalso include a second component comprising a polyisocyanate and/or ablocked polyisocyanate. The polyisocyanates can include aliphaticisocyanates, cycloaliphatic isocyanates, aromatic isocyanates, blockedaliphatic isocyanates, blocked cycloaliphatic isocyanates, blockedaromatic isocyanates, and combinations thereof.

Non-limiting examples of suitable polyisocyanates includetoluene-2,4-diisocyanate; toluene-2,6-diisocyanate; diphenylmethane-4,4′-diisocyanate; diphenyl methane-2,4′-diisocyanate;para-phenylene diisocyanate; biphenyl diisocyanate;3,3′-dimethyl-4,4′-diphenylene diisocyanate;tetramethylene-1,4-diisocyanate; hexamethylene-1,6-diisocyanate;2,2,4-trimethyl hexane-1,6-diisocyanate; 2,4,4-trimethylhexane-1,6-diisocyanate; lysine methyl ester diisocyanate;bis(isocyanato ethyl) fumarate; isophorone diisocyanate; ethylenediisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; methylcyclohexyl diisocyanate; hexahydrotoluene-2,4-diisocyanate;hexahydrotoluene-2,6-diisocyanate; hexahydrophenylene-1,3-diisocyanate;hexahydrophenylene-1,4-diisocyanate;perhydrodiphenylmethane-2,4′-diisocyanate;perhydrodiphenylmethane-4,4′-diisocyanate; and combinations thereof.

The polyisocyanates can also include modified polyisocyanates. The term“modified” means that the polyisocyanates are changed in a known mannerto introduce urea groups, carbodiimide groups, urethane groups,isocyanurate groups, thiourea groups, biuret groups, and combinationsthereof. Non-limiting examples of modified polyisocyanates includepolyureadiisocyanates, polyurethanediisocyanates,polythioureadiisocyanates, and combinations thereof. The modifiedpolyisocyanates can be prepared by reacting any of the previouslydescribed polyisocyanates with di-functional materials including, butnot limited to, polyols, amines, thiols, and combinations thereof.

Non-limiting examples of polyols that can be reacted with thepolyisocyanates to form a modified polyisocyanate include ethyleneglycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol,2,2,4-trimethyl-1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol,3-methyl-1,5-pentanediol, and combinations thereof. Non-limitingexamples of amine containing materials that can be reacted with thepolyisocyanates to form modified polyisocyanates include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6hexamethylene diamine, 1,3-cyclohexanediamine, 1,4-diaminocyclohexane,1,2-diaminocyclohexane, and combinations thereof. Non-limiting examplesof thiol containing materials that can be reacted with thepolyisocyanates to form modified polyisocyanates include1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol,1,5-pentanedithiol, 1,6-hexanedithiol, 2,3-butanedithiol,2,2′-(ethylenedioxy)diethanethiol, 3,6-dioxa-1,8-octanedithiol,ethyleneglycol bis(3-mercaptopropionate), dimercaptodiethyl sulfide(DMDS), and combinations thereof.

In addition, amino-alcohols, amino-thiols, thiol-alcohols,glycol-thioethers, and combinations thereof can also be reacted with thepolyisocyanates to form modified polyisocyanates. Non-limiting examplesof amino-alcohols include ethanolamine, 3-amino-1-propanol,4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol,3-amino-2-methylpropan-1-ol, 3-amino-2,2-dimethyl-1-propanol,3-aminobutan-1-ol, 1-amino-2-methylpropan-2-ol,3-methylamino-1-propanol, 4-methylamino-1-butanol,5-methyamino-1-pentanol, 6-methylamino-1-hexanol, and combinationsthereof. Non-limiting examples of thiol-alcohols include2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-1-propanol,2-mercapto-3-butanol, 3-mercapto-3-methylbutan-1-ol;4-mercapto-1-butanol, and combinations thereof. Further, theamino-thiols can include, but are not limited to, cysteamine and3-amino-1-propanethiol, and the glycol-thioethers can include, but arenot limited to, 2,2′-thiodiethanol. Non-limiting examples ofcommercially available modified polyisocyanates include the DESMODUR®isocyanates from Bayer and the VESTANAT® isocyanates from EvonikIndustries.

The blocked polyisocyanates that can be used as the second component canbe prepared by addition of a blocking group, for example β-diketone,phenol, 3,5-dimethylpyrazole, cresol, epsilon-caprolactam, and/or methylethyl ketoxime, to a compound containing free isocyanate functionalgroups such as any of the polyisocyanates previously described. Theblocked polyisocyanates can also include those commercially availablefrom Baxenden under the trade name TRIXENE®, such as TRIXENE® BI 7950,TRIXENE® BI 7951, TRIXENE® BI 7960, TRIXENE® BI 7961, TRIXENE® BI 7963,and TRIXENE® BI 7982. Other commercially available blockedpolyisocyanates include those commercially available from Bayer underthe trade name DESMODUR®, such as DESMODUR® BL 3175A, DESMODUR® BL 3272,DESMODUR® BL 3370, DESMODUR® BL 3475, and DESMODUR® BL 4265 SN.

The at least one photochromic compound that is combined with the firstand second components can be selected from inorganic and/or organicphotochromic compounds. When two or more photochromic compounds are usedin combination, they are generally chosen to complement one another toproduce a desired color or hue.

Non-limiting examples of organic photochromic compounds includebenzopyrans, naphthopyrans (for example naphtho[1,2-b]pyrans andnaphtho[2,1-b]pyrans) spiro-9-fluoreno[1,2-b]pyrans, phenanthropyrans,quinopyrans, and indeno-fused naphthopyrans, such as those disclosed inU.S. Pat. No. 5,645,767 at column 1, line 10 to column 12, line 57 andin U.S. Pat. No. 5,658,501 at column 1, line 64 to column 13, line 36,which disclosures are incorporated herein by reference. Additionalnon-limiting examples of organic photochromic compounds that may be usedinclude oxazines, such as benzoxazines, naphthoxazines, andspirooxazines. Other non-limiting examples of photochromic compoundsthat may be used include: fulgides and fulgimides, for example 3-furyland 3-thienyl fulgides and fulgimides, which are described in U.S. Pat.No. 4,931,220 at column 20, line 5 through column 21, line 38, whichdisclosure is incorporated herein by reference; diarylethenes, which aredescribed in U.S. Patent Application No. 2003/0174560 from paragraph[0025] to [0086], which disclosure is incorporated herein by reference;and combinations of any of the aforementioned photochromic compounds.

The photochromic compounds described herein can be incorporated into thecurable compositions by addition to the composition and/or by dissolvingit in a solvent before adding to the curable composition. Thephotochromic compounds can be added to the present compositions in anamount sufficient to produce a desired change in optical density (ΔOD)when the cured composition is exposed to radiation, such as ultraviolet(UV) radiation.

The curable photochromic compositions can include at least 0.2 weight %,at least 1 weight %, or at least 5 weight % of a photochromic compound.The curable photochromic compositions can also include up to 12 weight%, up to 10 weight %, or up to 8 weight % of a photochromic compound.The curable photochromic compositions can also include a range such asfrom 0.2 weight % to 12 weight %, or 4 weight % to 8 weight % of aphotochromic compound. The weight % of the photochromic compounds ineach case is based on the total solids weight of the curablephotochromic composition.

The curable photochromic compositions can also include a third componenthaving a second compound with three or more active hydrogen-functionalgroups and an active hydrogen-functional group equivalent weight of lessthan or equal to 500, such as less than or equal to 450, or less than orequal to 400, or less than or equal to 350, or less than or equal to300. The second compound can include various types of polyols,polyamines, polythiols, and combinations thereof and which have anactive hydrogen-functional group equivalent weight as previouslydescribed. For instance, the second compound can include acrylicpolyols, acrylic polyamines, and combinations thereof.

The acrylic polyols and polyamines that can be used as the secondcompound can be prepared from hydroxyl and amine containing(meth)acrylates. Examples of hydroxyl containing (meth)acrylatesinclude, but are not limited to, hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate,hydroxymethylethyl (meth)acrylate, hydroxymethylpropyl (meth)acrylate,and combination thereof. Examples of amine containing (meth)acrylatesinclude, but are not limited to, methacryloyl-L-lysine,N-(3-aminopropyl)methacrylamide, 2-aminoethyl methacrylate,2-(tert-Butylamino)ethyl (meth)acrylate, N-(2-aminoethyl)methacrylamide, and combinations thereof.

Non-limiting examples of polyols that can be used as the second compoundinclude pentaerythritol, 2-hydroxymethyl-1,3-propanediol,dipentaerythritol, 1,1,1-tris(hydroxymethyl)ethane,1,1,1-tris(hydroxymethyl)propane,2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol, and combinations thereof.Non-limiting examples of polyamines that can be used as the secondcompound of the third component include bis(3-aminopropyl)amine,triethylenetetramine, 1,2-bis(3-aminopropylamino)ethane,tetraethylenepentamine, tris[2-(methylamino)ethyl]amine, andcombinations thereof.

As indicated, polythiols can also be used as the second compound of thethird component. Non-limiting examples of suitable polythiols includepentaerythritol tetrakis(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), thioglycerol-bis(2-mercaptoacetate),trimethylolpropane tris(3-mercaptopropionate), trimethylolpropanetris(2-mercaptoacetate), and combinations thereof. Examples ofpolythiols are also disclosed in U.S. Patent Application Publication No.2009/0176945, which is incorporated by reference herein in its entirety.

Further, materials having both hydroxyl and thiol groups can be used asthe second compound. Non-limiting examples of such materials includeglycerin bis(2-mercaptoacetate), glycerin bis(3-mercaptopropionate),1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, trimethylolpropanebis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate),pentaerythritol bis(2-mercaptoacetate), pentaerythritoltris(2-mercaptoacetate), pentaerythritol bis(3-mercaptopropionate),pentaerythritol tris(3-mercaptopropionate), and combinations thereof.

The curable photochromic compositions of the present invention cancontain additional components that impart desired properties orcharacteristics to the composition, or which are used to apply and curethe photochromic compositions as coatings on the surface of a substrate.Such components include, but are not limited to, ultraviolet lightabsorbers, light stabilizers, such as hindered amine light stabilizers(HALS), asymmetric diaryloxalamide (oxanilide) compounds, singlet oxygenquenchers, antioxidants, heat stabilizers, rheology control agents,leveling agents, free radical scavengers, tinting agents, adhesionpromoting agents, such as trialkoxysilanes, and mixtures thereof.Catalysts may also be incorporated into the composition as necessary toeffect the chemical reactions for cure.

The first component, second component, at least one photochromiccompound, and, optionally, the additional components described herein,such as the third component, can be combined in one step to form acurable photochromic composition. Alternatively, a portion of the firstcomponent and a portion of the second component can be reactedseparately with either the second component or first component in excessto form an isocyanate functional prepolymer or anactive-hydrogen-functional prepolymer. The prepolymer can then becombined with a remainder of the first component and/or the secondcomponent, at least one photochromic compound, and, optionally, theadditional components described herein, such as the third component, toform a curable photochromic composition. For example, a diol can bereacted with an excess of a polyisocyanate or blocked polyisocyanate,such as a molar ratio of greater than 1:1 of the isocyanate: diol, toform a urethane prepolymer that is isocyanate functional. The isocyanatefunctional prepolymer can then be combined with additional diol, atleast one photochromic compound, and, optionally, the additionalcomponents described herein, such as the third component, to form acurable photochromic composition.

Further, the first and second components can be combined to form acurable photochromic composition with a ratio of total isocyanate andblocked isocyanate equivalents of the second component to total activehydrogen-functional group equivalents of the first component of at least4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least9:1, at least 10:1, or at least 15:1. The first and second componentscan also be combined to form a curable photochromic composition with aratio of total isocyanate and blocked isocyanate equivalents of thesecond component to total active hydrogen-functional group equivalentsof the first component of up to 100:1, up to 50:1, up to 30:1, up to25:1, or up to 20:1. The first and second components can further becombined to form a curable photochromic composition with a ratio rangeof total isocyanate and blocked isocyanate equivalents of the secondcomponent to total active hydrogen-functional group equivalents of thefirst component such as from 4:1 to 100:1, or from 5:1 to 30:1, or from6:1 to 20:1.

As used herein, the recitation of “total active hydrogen-functionalequivalents of the first component” means the total equivalents ofactive hydrogen-functional groups of the first component. As usedherein, the recitation of “total active hydrogen-functional equivalentsof the third component” means the total equivalents of activehydrogen-functional groups of the third component. The activehydrogen-functional groups can include, but are not limited to,hydroxyls, primary amines, secondary amines, thiols, and combinationsthereof, as described previously herein. Further, as used herein, therecitation of “total isocyanate and blocked isocyanate equivalents ofthe second component” means the total sum of isocyanate equivalents andblocked isocyanate equivalents of the second component.

In addition, the first, second, and third components can be combined toform a curable photochromic composition with a ratio of total isocyanateand blocked isocyanate equivalents of the second component to totalactive hydrogen-functional group equivalents of the first component andthe third component of at least 4:1, at least 5:1, at least 6:1, atleast 7:1, at least 8:1, at least 9:1, at least 10:1, or at least 15:1.The first, second, and third components can also be combined to form acurable photochromic composition with ratio of total isocyanate andblocked isocyanate equivalents of the second component to total activehydrogen-functional group equivalents of the first component and thethird component of up to 40:1, up to 30:1, up to 25:1, or up to 20:1.The first, second, and third components can further be combined to forma curable photochromic composition with a ratio range of totalisocyanate and blocked isocyanate equivalents of the second component tototal active hydrogen-functional group equivalents of the firstcomponent and the third component such as from 4:1 to 40:1, or from 5:1to 30:1, or from 6:1 to 20:1.

After forming the curable photochromic compositions, the compositionscan be applied to a surface of a substrate and cured to form a coatinglayer over at least a portion of the substrate, thereby forming aphotochromic article. Non-limiting examples of suitable substratesinclude, paper, glass, ceramics, wood, masonry, textiles, metals, andpolymeric organic host materials. The photochromic coatings areparticularly useful when applied to optical substrates, such as opticalsubstrates made from glass, minerals, ceramics, and metal.

Polymeric substrates that may be used in preparing the photochromicarticles of the present invention include organic polymeric materialsand inorganic materials, such as glass. As used herein, the term “glass”is defined as being a polymeric substance, for example a polymericsilicate. The glass substrate can be a clear, low colored, transparentglass such as the well-known silica type glass, particularlysoda-lime-silica glass. The nature and composition of various silicaglasses are well known in the art. The glass may be strengthened byeither thermal or chemical tempering.

Non-limiting examples of polymeric organic substrates include plasticmaterials that are chemically compatible with the photochromic coatingapplied to the surface of the substrate. The polymeric organic substratemay be prepared from art-recognized polymers that are useful as opticalsubstrates, such as organic optical resins that are used to prepareoptically clear castings for optical applications, such as ophthalmiclenses.

The photochromic compositions of the present invention can be applied tothe surface of a substrate by any means standard in the art, such asspin coating, printing, spraying, electrostatic spraying, dipping,rolling, brushing, curtain coating, and the like.

The photochromic compositions of the present invention can also be usedalone or in combination with additional layers. For example, the coatingcompositions can be applied over a primer coating. A “primer coating”refers to coating compositions from which an undercoating may bedeposited onto a substrate in order to prepare the surface forapplication of a protective or decorative coating system.

It was found that the coatings described herein comprise a plurality ofsoft segment domains formed from the first component and a plurality ofhard segment domains formed from the second component. When thecompositions include the third component previously described, the thirdcomponent can also form a portion of the hard segment domains of thecured coating. As such, the curable photochromic compositions can beapplied to a substrate and cured to form phase-separated coatings.Without being bound by theory, it is believed that the photochromiccompounds at least partially reside in the plurality of soft segmentdomains of the cured coatings.

The plurality of soft segment domains can have a size of less than 300nanometers (nm), less than 250 nm, less than 200 nm, less than 150 nm,or less than 100 nm. The domain sizes are determined by atomic forcemicroscopy (AFM), small angle x-ray scattering (SAXS), or transmissionelectron microscopy (TEM), for example. The plurality of soft segmentdomains can also have a glass transition temperature (Tg) of equal to orless than −10° C., or equal to or less than −50° C., or equal to or lessthan −100° C. The plurality of soft segment domains can have a Tg as lowas −150° C. The plurality of soft segment domains can also have a Tgrange such as from −10° C. to −150° C.

The plurality of hard segment domains can have a Tg of at least 0° C.,at least 50° C., at least 100° C., or at least 125° C. The plurality ofhard segment domains can have a Tg of up to 150° C. The plurality ofhard segment domains can also have a Tg range such as from 0° C. to 150°C. The Tg can be determined by dynamic mechanical analysis (DMA) ordifferential scanning calorimetry (DSC), for example.

Further, the coatings formed from the photochromic compositions canexhibit a Fischer microhardness of at least 10 N/mm², at least 25 N/mm²,at least 50 N/mm², or at least 100 N/mm². The coatings can also exhibita Fischer microhardness of up to 125 N/mm² or up to 150 N/mm². TheFischer microhardness is measured by a Fischerscope H100SMC stylusmicrohardness instrument following the instruction described in theFischerscope H100SMC Manual (“Fischer microhardness test”).

As indicated, the present invention is also directed to a photochromicarticle that comprises a substrate, such as an optical substrate, and atleast one photochromic coating layer as described herein residing overat least a portion the substrate. The photochromic articles of thepresent invention can be used in a variety of applications. For example,the photochromic articles may be designed for use on transparent, e.g.,optical, plastic, or glass substrates intended for ophthalmicapplications, such as vision correcting lenses, sun lenses and goggles,commercial and residential windows, automotive and aircrafttransparencies, helmets, clear films, and the like.

Further, the photochromic articles of the present invention can be usedin association with plastic or glass films and sheets, optical devices,e.g., optical switches, display devices and memory storage devices, suchas those described in U.S. Pat. No. 6,589,452, and security elements,such as optically-readable data media, e.g., those described in U.S.Patent Application No. 2002/0142248, security elements in the form ofthreads or strips, as described in U.S. Pat. No. 6,474,695, and securityelements in the form of verification marks that can be placed onsecurity documents and articles of manufacture.

The following examples are presented to demonstrate the generalprinciples of the invention. The invention should not be considered aslimited to the specific examples presented. All parts and percentages inthe examples are by weight unless otherwise indicated.

EXAMPLE 1 Preparation of a Polyester Polycarbonate Diol

A polyester polycarbonate diol was prepared from the components listedin Table 1.

TABLE 1 Component Weight (grams) ETERNACOLL ® UH-50 ¹ 250.1 Adipic acid67.16 Triphenyl phosphite 0.3 Dibutyltinoxide 0.3 ¹ Polycarbonate diolavailable from UBE Industries.

The components listed in Table 1 were added to a 500 ml 4-Neck roundbottom flask equipped with a mechanical stirrer and Dean-Stark trap. Themixture was heated to 140° C. under nitrogen, and stirred for one hour.The reaction was raised to 180° C. and stirred for an additional hour.Temperature was then raised to 200° C., and stirred for 11 hours. Thereaction was cooled to 120° C. under nitrogen and then to roomtemperature to yield a polyester polycarbonate diol with a numberaverage molecular weight (Mn) of 7,850 and a polydispersity of 2.02. Theacid value was less than 0.19 mg KOH/g (based on solids), and thehydroxyl equivalent weight was 2,318 based on solids.

EXAMPLE 2 Preparation of a Polycarbonate Diol

A polycarbonate diol was prepared according to the Polycarbonate PolyolB (PP-B) preparation in Part 1 of the Examples section of U.S. Pat. No.8,608,988 at column 19, lines 47-59, which is incorporated by referenceherein. The hydroxyl equivalent weight of the polycarbonate diol was1810 (based on solids). The final resin was reduced to 60% solids withdipropylene glycol methyl ether acetate (DPMA).

EXAMPLE 3 Preparation of an Active Hydrogen-Functional Prepolymer

An active hydrogen-functional prepolymer was prepared from thecomponents listed in Table 2.

TABLE 2 Component Weight (grams) DURANOL ® T5652A ² 181.9N-methyl-2-pyrrolidone 131.9 VESTANAT ® TMDI ³ 15.6 K-KAT ® 348 ⁴ 0.34 ²Polycarbonate diol available from Asahi Kasei Chemicals Corporation.

In accordance with Table 1, DURANOL® T5652A was mixed under nitrogenwith N-methyl-2-pyrrolidone and VESTANAT® TMDI for 15 minutes followedby addition of K-KAT® 348. The reaction mixture was stirred at roomtemperature for one hour and then heated to 80° C. for three hours untilall free isocyanates were consumed, as determined by FTIR spectroscopy.The reaction mixture was cooled to room temperature and the resultingclear, viscous polymer solution was collected. The final product had anumber average molecular weight (Mn) of 16,600, a weight averagemolecular weight (Mw) of 32,200, and 59.7% total solids. The theoreticalactive hydrogen equivalent weight of the material was 5,011 based onsolids.

EXAMPLE 4 Preparation of an Isocyanate Functional Prepolymer

An active isocyanate functional prepolymer was prepared from thecomponents listed in Table 3.

TABLE 3 Component Weight (grams) Polycarbonate diol of Example 2 30VESTANAT ® TMDI ³ 14.6 Dibutyltin dilaurate 0.05 Di(propylene glycol)methyl ether acetate 4 3,5-Dimethylpyrazole 10.9

In accordance with Table 3, the polycarbonate diol of Example B wasadded dropwise into a 40° C. solution of VESTANAT® TMDI anddibutyltindilaurate, followed by a rinse with di(propylene glycol)methyl ether acetate. The solution was heated to 60° C. for 1.5 hours.3,5-dimethylpyrazole was then added in portions until isocyanate was notobserved by FTIR spectroscopy. The reaction mixture was cooled toprovide a viscous oil with a solids content of 73% (one hour, 120° C.).The number average molecular weight (Mn) of the polymer portion was7,390 and the weight average molecular weight (Mw) was 9,850. Theisocyanate equivalent weight of the sample was 400 based on solids.

EXAMPLE 5 Preparation of a Polyureapolyurethane Diisocyanate

A polyureapolyurethane diisocyanate was prepared from the componentslisted in Table 4.

TABLE 4 Component Weight (grams) Hexafluoropentanediol 3Hexamethylenediamine 1.6 VESTANAT ® TMDI ³ 11.9 Dibutyltin dilaurate0.05 N-methyl-2-pyrrolidone 11.5 3,5-Dimethylpyrazole 5.35

In accordance with Table 4, a solution of hexafluoropentanediol,hexamethylenediamine, and 3,5-dimethylpyrazole in N-methyl-2-pyrrolidonewas added dropwise to a solution of VESTANAT® TMDI anddibutyltindilaurate at 40° C. After rinsing with N-methyl-2-pyrrolidonethe reaction mixture was stirred at 65° C. for two hours. Additional3,5-dimethylpyrazole was then added in portions until isocyanate was notobserved by FTIR spectroscopy. The reaction mixture was cooled toprovide a viscous oil with a solids content of 68%. The isocyanateequivalent weight of the sample was 410 based on solids.

EXAMPLES 6-16 Preparation of Curable Photochromic Compositions

Curable photochromic compositions were prepared from the componentslisted in Tables 5 and 6. All components are listed in parts per weightand quantities in Charge 2 are listed by solid component only.

TABLE 5 Comparative Comparative Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11Charge 1 Photochromic dyes ⁵ 4.00 3.99 4.11 3.99 4.01 3.96 TINUVIN ® 144⁶ 2.00 2.00 2.00 2.02 1.82 Stabilizer ⁷ 1.97 IRGANOX ® 245 ⁸ 2.00 2.001.95 2.00 2.02 1.82 N-methyl-2-pyrrolidone 55.33 34.08 67.93 37.17 32.7235.65 Charge 2 ETERNACOLL ® PH200D ⁹ 33.18 Compound of Example 1 35.83Compound of Example 2 33.18 33.16 31.36 Compound of Example 3Poly(ethylene glycol- ran-propylene glycol) ¹⁰ K-KAT ® 348 ⁴ 0.74 0.771.10 0.72 0.79 0.90 SILQUEST ® A-187 ¹¹ 3.98 3.85 6.20 3.88 4.05 5.31Acrylic polyol ¹² 22.69 17.84 3.48 5.05 TRIXENE ® BI-7960 ¹³ 44.13 48.9764.17 63.36 29.32 49.87 Compound of Example 4 65.63 Compound of Example5 18.76 BYK ® 333 ¹⁴ 0.07 0.07 0.09 0.07 0.09 0.11 Solvent from resins¹⁵ 34.02 55.20 28.70 52.28 40.26 51.42 % Solids (theory) 55.8 55.8 54.455.7 60.8 56.7

TABLE 6 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Charge 1 Photochromic dyes ⁵4.01 4.01 4.01 4.04 3.99 TINUVIN ® 144 ⁶ 2.01 2.01 2.01 2.01 1.99Stabilizer ⁷ IRGANOX ® 245 ⁸ 2.00 2.00 2.00 2.01 1.99N-methyl-2-pyrrolidone 33.87 33.87 33.87 24.84 25.81 Charge 2ETERNACOLL ® PH200D ⁹ Compound of Example 1 Compound of Example 2 28.3931.30 34.16 Compound of Example 3 31.82 Poly(ethylene glycol-ran- 31.48propylene glycol) ¹⁰ K-KAT ® 348 ⁴ 0.91 0.91 0.91 0.87 0.79 SILQUEST ®A-187 ¹¹ 4.53 4.53 4.53 4.19 3.92 Acrylic polyol ¹² 9.16 6.26 3.41 4.253.38 TRIXENE ® BI-7960 ¹³ 62.45 62.44 62.43 63.93 65.13 Compound ofExample 4 Compound of Example 5 BYK ® 333 ¹⁴ 0.11 0.11 0.11 0.11 0.14Solvent from Resins ¹⁵ 51.74 51.86 51.97 70.24 35.07 % Solids (theory)57.0 57.0 57.0 54.4 65.0

For each coating composition shown in Tables 5 and 6, the components ofCharge 1 were added to a suitable vessel with stirring and heated to40-60° C. for a minimum of 30 minutes until the solids dissolved. Theingredients of Charge 2 were combined, mixed thoroughly, and then addedto the solution of Charge 1. The resulting mixture was placed on aWHEATON® 348923-A Benchtop Roller, available from Wheaton Industries,Inc., for a minimum of six hours prior to use. The centi-equivalents(cEq) and resulting NCO to active hydrogen ratios for each Example areshown in Table 7.

TABLE 7 cEq 1^(st) cEq 2^(nd) cEq 3^(rd) NCO:Active Example ComponentComponent Component Hydrogens 6 3.38 15.38 6.30  1.6:1.0¹⁶ 7 1.77 17.064.96 2.5:1.0 8 1.55 22.36 — 14.4:1.0  9 1.77 22.08 0.97 8.1:1.0 10 1.4731.43 1.40 10.9:1.0  11 1.73 21.92 — 12.6:1.0  12 1.57 21.76 2.545.3:1.0 13 1.73 21.76 1.74 6.3:1.0 14 1.89 21.75 0.95 7.7:1.0 15 3.0324.67 1.18 5.9:1.0 16 0.52 22.70 0.94 15.5:1.0  ¹⁶The first component ofComparative Example 6 comprises a polyol having an equivalent weight of983.

EXAMPLE 17 Application of Photochromic Coatings

The compositions of Examples 6-9 and 11-16 were each applied to a PDQ®coated Gentex® polycarbonate plano lens having a diameter of 76millimeters. The composition of Example 10 was applied to 2″×2″ CR-39chips from Homalite of Wilmington, Del. All substrates were treated withoxygen plasma at a flow rate of 100 milliliters (mL) per minute ofoxygen at 100 watts of power for three minutes prior to being coatedwith the compositions of Examples 6-16 via a spin coating process. About1-2 mL of each composition was dispensed onto the substrate and thenrotated for eight seconds at a spin speed sufficient to deposit0.25-0.35 g of wet coating onto the lens or about 0.15-0.19 g of wetcoating onto the CR39 chip. The spin coating parameters are shown inTable 8 below.

TABLE 8 Photochromic Spin Time Spin speed coating weight ExampleSubstrate (sec) (rpm) (g) 6 Polycarbonate Lens 8 916 0.27 7Polycarbonate Lens 8 976 0.26 8 Polycarbonate Lens 8 916 0.27 9Polycarbonate Lens 8 916 0.26 10 CR39 Chip 8 1308 0.16 11 PolycarbonateLens 8 1112 0.25 12 Polycarbonate Lens 8 916 0.30 13 Polycarbonate Lens8 916 0.31 14 Polycarbonate Lens 8 916 0.31 15 Polycarbonate Lens 121157 0.35 16 Polycarbonate Lens 8 1399 0.30

The coated substrates were made in duplicate and designated as Set “A”and Set “B”. The coated substrates were then placed in a 40° C. ovenuntil all lenses or chips were accumulated. The chips or lenses werethen cured in a forced air oven at 125° C. for one hour and subsequentlycooled to room temperature. The lenses and chip of Set “A” were thensubjected to an additional thermal cure for three hours at 105° C. andset aside for evaluation. The lenses and chip of Set “B” were furthertreated with oxygen plasma as previously described and coated with aprotective coating according to the formulation reported in Table 1 ofExample 1 in U.S. Pat. No. 7,410,691, which is incorporated herein byreference, using an additional 0.5% polybutyl acrylate. The protectivecoating was applied by spin coating and UV cured in an EyeUV ovenequipped with D bulbs. Following this, each lens or chip was furthercured at 105° C. for three hours. The lenses and chip of Set “B” werethen evaluated for photochromic properties.

EXAMPLE 18 Microhardness and Photochromic Performance Evaluation

The coated substrates of Set “A” of Example 17 were subjected tomicrohardness testing using a Fischerscope HCV, Model H100SMC availablefrom Fischer Technology, Inc. Each lens was measured from 2 to 5 timesand the resulting data was averaged. The hardness measurements weretaken as the hardness at a penetration depth of 2 microns after a 100Newton load for 15 seconds.

In addition, the photochromic performance of the coated substrates ofSet “B” of Example 17 were tested on the Bench for MeasuringPhotochromics (“BMP”) made by Essilor, Ltd. France. The optical benchwas maintained at a constant temperature of 73.4° F. (23° C.) duringtesting. Prior to testing on the optical bench, each of the coatedlenses were exposed to 365-nanometer ultraviolet light for about 10minutes at a distance of about 14 centimeters to activate thephotochromic materials. The UVA (315 to 380 nm) irradiance at the lenswas measured with a LICOR® Model Li-1800 spectroradiometer and found tobe 22.2 watts per square meter. Each lens was then placed under a 500watt, high intensity halogen lamp for about 10 minutes at a distance ofabout 36 centimeters to bleach (inactivate) the photochromic materials.The illuminance at the lens was measured with the LICOR®spectroradiometer and found to be 21.9 Klux. Each lens was then kept ina dark environment at room temperature (from 70 to 75° F., or 21 to 24°C.) for at least one hour prior to testing on an optical bench. Prior tomeasurement, each lens was measured for ultraviolet absorbance at 390nanometers.

The BMP optical bench was fitted with two 150-watt Newport Model #6255Xenon arc lamps set at right angles to each other. The light path fromLamp 1 was directed through a 3 mm SCHOTT® KG-2 band-pass filter andappropriate neutral density filters that contributed to the required UVand partial visible light irradiance level. The light path from Lamp 2was directed through a 3 mm SCHOTT® KG-2 band-pass filter, a SCHOTT®short band 400 nm cutoff filter and appropriate neutral density filtersin order to provide supplemental visible light illuminance A 2 inch×2inch 50% polka dot beam splitter set at 45° to each lamp is used to mixthe two beams. The combination of neutral density filters and voltagecontrol of the Xenon arc lamp were used to adjust the intensity of theirradiance. Software i.e., BMPSoft version 2.1e was used on the BMP tocontrol timing, irradiance, air cell and sample temperature, shuttering,filter selection, and response measurement. A ZEISS® spectrophotometer,Model MCS 601, with fiber optic cables for light delivery through thelens was used for response and color measurement. Photopic responsemeasurements were collected on each lens.

The power output of the optical bench, i.e., the dosage of light thatthe lens was exposed to, was adjusted to 6.7 watts per square meter(W/m2) UVA, integrated from 315-380 nm, and 50 Klux illuminance,integrated from 380-780 nm. Measurement of this power setpoint was madeusing an irradiance probe and the calibrated Zeiss spectrophotometer.The lens sample cell was fitted with a quartz window and self-centeringsample holder. The temperature in the sample cell was controlled at 23°C. through the software with a modified Facis, Model FX-10, environmentsimulator. Measurement of the sample's dynamic photochromic response andcolor measurements were made using the same Zeiss spectrophotometer withfiber optic cables for light delivery from a tungsten halogen lampthrough the sample. The collimated monitoring light beam from the fiberoptic cable was maintained perpendicular to the test sample whilepassing through the sample and directed into a receiving fiber opticcable assembly attached to the spectrophotometer. The exact point ofplacement of the sample in the sample cell was where the activatingxenon arc beam and the monitoring light beam intersected to form twoconcentric circles of light. The angle of incidence of the xenon arcbeam at the sample placement point was ≈30° from perpendicular.

Response measurements, in terms of a change in optical density (*OD)from the unactivated or bleached state to the activated or colored statewere determined by establishing the initial unactivated transmittance,opening the shutter from the Xenon lamp(s) and measuring thetransmittance through activation at selected intervals of time. Changein optical density was determined according to the formula: *OD=log₁₀(%Tb/% Ta), where % Tb is the percent transmittance in the bleached stateand % Ta is the percent transmittance in the activated state. Opticaldensity measurements were based on photopic optical density.

The results of the microhardness and photochromic performance are shownin Table 9. The ΔOD at saturation is after 15 minutes of activation andthe Fade Half Life (“T½”) value is the time interval in seconds for theΔOD of the activated form of the photochromic material in the coating toreach one half the fifteen-minute ΔOD at 73.4° F. (23° C.), afterremoval of the activating light source.

TABLE 9 NCO:OH Fischer microhardness T½ @ Photopic Example (OH = 1.0)(N/mm²) (seconds) 6 1.6 28 131 7 2.5 35 109 8 14.4 11 97 9 8.1 28 101 1018.9 17 93 11 12.6 19 103 12 5.3 43 104 13 6.3 28 100 14 7.7 18 99 159.2 30 101 16 15.5 24 77

As shown in Table 9, the photochromic coatings of Examples 8-16, whichhad a NCO:OH ratio of at least 4:1, exhibited superior photochromicperformance with good hardness as compared to Comparative Examples 6 and7, which had a NCO:OH ratio of less than 4:1.

EXAMPLE 19 Dynamic Mechanical Analysis

Examples 6, 7, 9, and 16 were evaluated for dynamic mechanical analysis(DMA) using TA Instruments 2980 DMA unit in tension film mode. Amplitudewas set at 20 μm, preload force of 0.01N, force track of 150% andfrequency of 1 Hz. The temperature cycle chosen was −100 to 175° C. witha heating rate of 3° C./minute. Clamping force of 20 cNm was also used.Sample dimensions were 15 mm×6.4 mm with a thickness of 20-30 μm. TheDMA results are shown in Table 10.

TABLE 10 Peak 1 Peak 2 Tan Delta Peak 1 Tan Delta Peak 2 Phase Fade T½Example (Tg, ° C.) Description (Tg, ° C.) Description Separation (sec.)6 55 Major Peak −14 Very Minor Very Slight 131 Shoulder 7 71 Major Peak−20 Minor Slight 109 Shoulder 9 70 Major Peak −19 Separate Moderate 101Peak 16 93 Major Peak −68 Major Peak Substantial 77

Dynamic mechanical analysis (DMA) can relate to the miscibility of thepolymer blend. Two separate Tg peaks means a heterogeneous system inwhich the two polymers exist as separate phases. One single peakindicates that the polymer blend is completely miscible. There is acontinuum between these two states. As shown in Table 10, ComparativeExamples 6 and 7 show a shoulder as the low Tg material. Example 9 showsa much more pronounced peak at a low Tg indicating increased separationbetween the hard and soft polymer domains Example 16 shows an evengreater degree of phase separation as evidenced by the increasedseparation of its two peaks.

The present invention is also directed to the following clauses.

Clause 1: A curable photochromic composition comprising: (a) a firstcomponent comprising a first compound having at least two activehydrogen-functional groups and an active hydrogen-functional groupequivalent weight of at least 1000; (b) a second component comprising atleast one of a polyisocyanate and a blocked polyisocyanate; and (c) atleast one photochromic compound, wherein the ratio of total isocyanateand blocked isocyanate equivalents of the second component to totalactive hydrogen-functional group equivalents of the first component isat least 4:1.

Clause 2: The curable photochromic composition of clause 1, furthercomprising: (d) a third component comprising a second compound havingthree or more active hydrogen-functional groups and an activehydrogen-functional group equivalent weight of less than or equal to500, wherein the ratio of total isocyanate and blocked isocyanateequivalents of the second component to total active hydrogen-functionalgroup equivalents of the first and third components is at least 4:1.

Clause 3: The curable photochromic composition of clause 1, wherein theratio of total isocyanate and blocked isocyanate equivalents of thesecond component to total active hydrogen-functional groups equivalentsof the first component is at least 5:1.

Clause 4: The curable photochromic composition of clause 1, wherein theratio of total isocyanate and blocked isocyanate equivalents of thesecond component to total active hydrogen-functional groups equivalentsof the first component is up to 50:1.

Clause 5: The curable photochromic composition of any of clauses 1-4,wherein the second component (b) comprises a polyureadiisocyanate, ablocked polyureadiisocyanate, a polyurethanediisocyanate, a blockedpolyurethanediisocyanate, a polythiourethanediisocyanate, a blockedpolythiourethanediisocyanate, or combinations thereof.

Clause 6: The curable photochromic composition of any of clauses 1-5,wherein the curable photochromic composition comprises a prepolymercomprising a reaction product of (a) and (b).

Clause 7: The curable photochromic composition of any of clauses 1-6,wherein the first compound and second compound each independentlycomprise active hydrogen-functional groups chosen from hydroxyls,primary amines, secondary amines, thiols, or combinations thereof.

Clause 8: The curable photochromic composition of any of clauses 1-7,wherein the first compound and/or the second compound each independentlycomprise a polyol.

Clause 9: The curable photochromic composition of any of clauses 1-8,wherein the polyol of the first compound is independently selected frompolyether polyols, polyester polyols, polycarbonate polyols, orcombinations thereof.

Clause 10: The curable photochromic composition of any of clauses 2-9,wherein the polyol of the second compound comprises an acrylic polyol.

Clause 11: The curable photochromic composition of any of clauses 1-10,wherein the at least one photochromic compound is an organicphotochromic material selected from photochromic spirooxazines,benzopyrans, naphthopyrans, indenonaphthopyrans, fulgides, metaldithizonates, diarylethenes, or combinations thereof.

Clause 12: The curable photochromic composition of any of clauses 1-11,wherein when applied to a substrate and cured to form a coating, thefirst component forms a plurality of soft segment domains and the secondcomponent forms a plurality of hard segment domains

Clause 13: The curable photochromic composition of any of clauses 2-12,wherein when applied to a substrate and cured to form a coating, thefirst component forms a plurality of soft segment domains and the secondand third components together form a plurality of hard segment domains.

Clause 14: The curable photochromic composition of any of clauses 12-13,wherein the plurality of soft segment domains have a Tg of −10° C. to−150° C., and the plurality of hard segment domains have a Tg of 0° C.to 150° C.

Clause 15: The curable photochromic composition of claim of any ofclauses 12-14, wherein the plurality of soft segment domains eachcomprise a size of less than 300 nm.

Clause 16: The curable photochromic composition of any of clauses 12-14,wherein the plurality of soft segment domains each comprise a size ofless than 100 nm.

Clause 17: The curable photochromic composition of claim of any ofclauses 12-16, wherein the at least one photochromic compound at leastpartially resides in the plurality of soft segment domains formed fromthe first component.

Clause 18: The curable photochromic composition of any of clauses 1-17,wherein when applied to a substrate and cured to form a coating, thecoating exhibits a Fischer microhardness of at least 10 N/mm².

Clause 19: A photochromic article comprising: (a) a substrate; and (b)at least one coating layer formed from the composition of any of clauses1-18 residing over at least a portion of the substrate.

Clause 20: The photochromic article of clause 19, wherein the substrateis an optical substrate.

Clause 21: The photochromic article of any of clauses 19-20, wherein theratio of total isocyanate and blocked isocyanate equivalents of thesecond component to total active hydrogen-functional group equivalentsof the first component is at least 5:1.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

1. A curable photochromic composition comprising: (a) a first componentcomprising a first compound having at least two activehydrogen-functional groups and an active hydrogen-functional groupequivalent weight of at least 1000; (b) a second component comprising atleast one of a polyisocyanate and a blocked polyisocyanate; and (c) atleast one photochromic compound, wherein the ratio of total isocyanateand blocked isocyanate equivalents of the second component to totalactive hydrogen-functional group equivalents of the first component isat least 4:1.
 2. The curable photochromic composition of claim 1,further comprising: (d) a third component comprising a second compoundhaving three or more active hydrogen-functional groups and an activehydrogen-functional group equivalent weight of less than or equal to500, wherein the ratio of total isocyanate and blocked isocyanateequivalents of the second component to total active hydrogen-functionalgroup equivalents of the first component and the third component is atleast 4:1.
 3. The curable photochromic composition of claim 1, whereinthe ratio of total isocyanate and blocked isocyanate equivalents of thesecond component to total active hydrogen-functional groups equivalentsof the first component is at least 5:1.
 4. The curable photochromiccomposition of claim 1, wherein the ratio of total isocyanate andblocked isocyanate equivalents of the second component to total activehydrogen-functional groups equivalents of the first component is up to50:1.
 5. The curable photochromic composition of claim 1, wherein thepolyisocyanate of the second component (b) is selected from apolyureadiisocyanate, a blocked polyureadiisocyanate, apolyurethanediisocyanate, a blocked polyurethanediisocyanate, apolythiourethanediisocyanate, a blocked polythiourethanediisocyanate,and combinations thereof.
 6. The curable photochromic composition ofclaim 1, wherein the curable photochromic composition further comprisesa prepolymer comprising a reaction product of (a) and (b).
 7. Thecurable photochromic composition of claim 2, wherein the first compoundand the second compound each independently comprise activehydrogen-functional groups chosen from hydroxyls, primary amines,secondary amines, thiols, or combinations thereof.
 8. The curablephotochromic composition of claim 2, wherein the first compound and/orthe second compound each independently comprise a polyol.
 9. The curablephotochromic composition of claim 8, wherein the polyol of the firstcompound is independently selected from polyether polyols, polyesterpolyols, polycarbonate polyols, and combinations thereof.
 10. Thecurable photochromic composition of claim 8, wherein the polyol of thesecond compound comprises an acrylic polyol.
 11. The curablephotochromic composition of claim 1, wherein the at least onephotochromic compound is an organic photochromic material selected fromphotochromic spirooxazines, benzopyrans, naphthopyrans,indenonaphthopyrans, fulgides, metal dithizonates, diarylethenes, orcombinations thereof.
 12. The curable photochromic composition of claim1, wherein when applied to a substrate and cured to form a coating, thefirst component forms a plurality of soft segment domains and the secondcomponent forms a plurality of hard segment domains.
 13. The curablephotochromic composition of claim 2, wherein when applied to a substrateand cured to form a coating, the first component forms a plurality ofsoft segment domains and the second component and the third componenttogether form a plurality of hard segment domains.
 14. The curablephotochromic composition of claim 12, wherein the plurality of softsegment domains have a Tg of −10° C. to −150° C., and the plurality ofhard segment domains have a Tg of 0° C. to 150° C.
 15. The curablephotochromic composition of claim 12, wherein the plurality of softsegment domains each comprise a size of less than 300 nm.
 16. Thecurable photochromic composition of claim 12, wherein the plurality ofsoft segment domains each comprise a size of less than 100 nm.
 17. Thecurable photochromic composition of claim 12, wherein the at least onephotochromic compound at least partially resides in the plurality ofsoft segment domains formed from the first component.
 18. The curablephotochromic composition of claim 1, wherein when applied to a substrateand cured to form a coating, the coating exhibits a Fischermicrohardness of at least 10 N/mm².
 19. A photochromic articlecomprising: (a) a substrate; and (b) at least one coating layer, formedfrom the curable photochromic composition of claim 1 residing over atleast a portion of the substrate.
 20. The photochromic article of claim19, wherein the substrate is an optical substrate.
 21. The photochromicarticle of claim 19, wherein the ratio of total isocyanate and blockedisocyanate equivalents of the second component to total activehydrogen-functional groups equivalents of the first component is atleast 5:1.
 22. The curable photochromic composition of claim 13, whereinthe plurality of soft segment domains have a Tg of −10° C. to −150° C.,and the plurality of hard segment domains have a Tg of 0° C. to 150° C.23. The curable photochromic composition of claim 13, wherein theplurality of soft segment domains each comprise a size of less than 300nm.
 24. The curable photochromic composition of claim 13, wherein theplurality of soft segment domains each comprise a size of less than 100nm.
 25. The curable photochromic composition of claim 13, wherein the atleast one photochromic compound at least partially resides in theplurality of soft segment domains formed from the first component.